Although substantial research exists on the impact of having a sibling with a chronic disease, almost nothing is known about how the etiology of the condition influences an adolescent sibling's experience. While studies have provided insight into adult siblings' feelings about and understanding of reproductive risks, carrier status, and carrier testing, and have provided insight into family communication, they only touch on the experiences of adolescents retrospectively, from an adult perspective. Lack of insight into siblings' experiences, attitudes, and questions compromises both the provision of effective genetic counseling and the basis of policy decisions regarding carrier testing for adolescents in these families. To explore adolescent sisters' (1) perception of reproductive risks, (2) resources for information and support, and (3) attitudes toward the appropriate age for risks and benefits of carrier testing, we are conducting ongoing telephone interviews with parents and adolescent sisters (age 12-17) of individuals with chronic granulomatous disease (CGD), spinal muscular atrophy types II and III (SMA), and Duchenne (DMD) and Becker (BMD) muscular dystrophy. Interviews of families affected by CGD have been completed. Of the 105 families responded to our letter of invitation by expressing interest in participating in the study, 14 included an adolescent sister of a person with CGD and hence were eligible to be interviewed. Ten of these families (including 10 mothers, 4 fathers, and 9 girls) were interviewed. Analysis of the transcribed interviews of parents and sisters of individuals with CGD has also been completed. Of the 83 families with DMD, BMD, or SMA who replied to our letter of invitation by expressing interest in participating, 10 included an adolescent sister. Two of these families have been interviewed, and informed consent forms have been sent, but interviews not yet conducted for an additional three. We are still in the process of contacting four of the families. Only one family with an adolescent sister was affected by SMA. Due to the limits of information which could be derived from interviewing one family, I decided against conducting those interviews. Analysis of these transcripts has not yet begun.